We have had no problems taking them in the blister packs. It is wise to take a few extra days suplies just in case of delays. If you have a problem on the ship the Medical unit is usually quite good if you did have a problem. This year we omitted one tablet but were able to buy replacements, if they don't have them in stock they can often pick them up at the next port of call but better not to make our mistake if you can.

Both my partner and I need to take tablets daily, she takes them in the daily plastic dispencers and she takes her insulin loose. I take mie in the blister packs and we have not encountered any problems, wev`e been on 3 cruises with Thompson, NCL, and RCL.
Be sure to inform them if you are diabetic type 1 and they will provide you with a sharps box.